Form for casting concrete subgrade stair structures



March 21, 1967 w. c. LYONS 3,310,275

7 FORM FOR CASTING CONCRETE SUBGRADE STAIR STRUCTURES Filed March 8, 1965 4 Sheets-Sheet 1 I 42 40 \42) INVENTOR H6 3 42 4 WILl /AM c. LVONS g BY flz L-wflza z ATTORNEYS March 21, 1967 w. c. LYONS FORM FOR CASTING CONCRETE SUBGRADE STAIR STRUCTURES 4 Sheets-Sheet 2 Filed March 8, 1965 R m o my W 1C M M u l W ATTORNEVS March 21, 1967 w. (3. LYONS FORM FOR CASTING CONCRETE SUBGRADE STAIR STRUCTURES 4 Sheets-Sheet 5 Filed March 8, 1965 INVENTOR. WILLIAM C- LVONS ATTORNEY March 21, 1967 w. c. LYONS 3,

FORM FOR CASTING CONCRETE SUBGRADE STAIR STRUCTURES 4 Sheets-Sheet 4 Filed March 8, 1965 INVENTOR. WIL LIAM C. LVONS ATTORNEYS United States Patent 3,310,275 FORM FOR CASTING CONCRETE SUBGRADE STAIR STRUCTURES William C. Lyons, 186 Damascus Road, Branford, Conn. 06405 Filed Mar. 8, 1965, Ser. No. 437,847

'7 Claims. (Cl. 249-14) This invention relates generally to forms for use in precasting concrete stair structures, and more particularly for producing a'concrete su bgrade stairwell and flight of stairs of monolithic structure of the type used to provide outside access to interior building areas wholly or partially below grade. I

The advantages of unitary or monolithic concrete stair structures from the standpoint of superior serviceability, improved manufacturing economies and simplified installation procedures is well known in the art, and numerous proposals for this general type of structure have been made heretofore. One such proposal is shown in my earlier Patent No. 3,147,531, granted Sept. 8, 1964, in which there is described a form that is particularly useful in casting a unitary stairwell and stair flight in place against a previously erected basement or subgrade foundation wall. This unit hasproved quite satisfactory in actual practice. There are, however, advantages to be realized many times by precasting such stair structures on a mass production basis at a location remote from the actual points of installation, and then transporting the precast structure to the construction site for installation. A particularly suitable precast stairway construction of this type is shown and disclosed in my co-pendirig applica tion Ser. No. 373,802, filed June 9, 1964. 7

It is a principal object of the present invention to make further improvements in this art by provision of a form for casting concrete stair structures on a mass production basis, wherein the form provides novel features of construction which, in combination, produce greater ease of fabricating the precast stair structures, as well as a structurally and functionally improved final product. As used herein the term stair structure defines a stairwell comprising generally right-triangular side or retaining walls which flank a flight of treads and risers, to provide a laterally enclosed stairway to a subgrade entry in a building.

In brief, the invention herein disclosed is based on the concept of casting a unitary subgrade stair structure in which the form is so adapted and arranged that, during the casting operation, the plane of the stair flight, i.e. the plane tangent to the noses of the threads in the flight, is disposed substantially horizontally. In other words, during the casting operation the stair structure is in an upside down position relative to its final installed position at a building site. As will appear more fully from the following description, this concept embodies a casting form of unique design which minimizes the number of form elements required and simplifies the stripping of these and removal of the finished casting from the form.

The invention is illustrated by the several form structures shown-in the accompanying drawings and described hereinafter. In the drawings,

FIG. 1 is a view in side elevation of an assembled form, ready to receive fluid concrete;

FIG. 2 is another view in side elevation, in section on line 22 of FIG. 3;

FIG. 3 is a plan view as seen from above in FIG. 1;

FIG. 4 is a cross-sectional view in end elevation, taken on line 445YFIG. 3;

FIG. 5 is a fragmentary sectional view of a corner detail, taken on line 55 of FIG. 3;

' FIG. 6 is a fragmentary sectional view in end elevation showing a finished'casting being lifted from the form;

3,31%,275 Patented Mar. 21, 1967 ice FIGS. 7 and 8 are fragmentary cross-sectional views in end elevation of a modification of the form shown in FIGS. 1 through 6;

FIGS. 9 and 10 are, similarly, partial cross-sectional views in end elevation of another type of form wherein the side panels themselves are employed to lift the finished casting free of the form; and I FIGS. 11 and 12 are further illustrations, similar to the foregoing, of other modifications of which the invention is capable.

Referring first to FIGS. 1 through 6 of the drawings for a general understanding of the novel casting form, it will be seen that in side elevation the form takes the appearance of a substantially right-angled equilateral trian le supported on its apex with its hypotenuse edge run ning generally horizontally. As seen in end elevation in FIG. .4, the form is of inverted U-shape, with the lateral walls constituting the legs of the U, and the stair flight forming member constituting the bridging section or web between the legs. hydrostatic pressures of the poured concrete, the panel members are preferably formed of steel plates and reinforcing angles or channels, welded together to build up the respective members, as more fully described hereinafter.

Looking at the assembled form in plan as shown in FIG. 3, the form is generally rectangular in shape, with relatively deep triangular prismatic voids flanking a central, relatively shallow, saw-toothed-bottom, bridging cavity. The form is thus open at the top and may be easily filled from above with a fluid concrete mix to the level of the upper edges of the form.

After allowing the casting to set, by removing the two outer right-triangular side panels of the form, the finished casting may be lifted vertically from the inner, stationary portion of the form in simple manner. In the examples of FIGS. 1 to 8, suitable hoist attachments are embedded in the concrete casting after the concrete has'been poured and before it is set. Alternate arrangements, whereby the outer sidewalls of the form are themselves used as a hoisting means eliminating the necessity for separate hoist attachments, are shown in FIGS. 9 to 12 of the drawings.

From as seen in FIGS. 1 to 5 is permanently supported upon a horse 22. The form includes sets of two inner and two outer side panels 24, 26 respectively, which areof generally right equilateral triangular form. Inner panels 24 are permanently secured to struts or legs 28 of the horse 22, with their apexes at the bottom, thus disposing the upper hypotenuse edges of each substantially horizontal. Legs 23 are slightly splayed, whereby inner panels 24 are located in generally vertical planes which diverge slightly toward the apex of the triangular sections. Suitable cross-bracing 29 maintain the legs in this splayed position. This produces a draft or relief in the form for easy removal of the finished casting, as will appear more fully hereinafter.

The upper, horizontal edges 30 of each of the inner panels 24 is of saw-tooth contour, as seen best in FIG. 2, and a fabricated saw-toothed plate or web section 32, conforming to the tread and riser contour of the finished casting, is nested in and permanently joined, as by welding, along its opposite edges, to the mating edges 30 of the inner panels 24.

Along each of the right-angularly related under edges of the inner panels 24, there are permanently secured laterally extending flanges 38, 40, respectively, of substantial width, which flanges form with panels 24 a laterally, outwardly open V-shaped trough, one on each side of the form. These lateral flanges extend beyond the respective ends of panels 24 and web plate 32, and filler panels 34, 36 extend between and are permanently In order to withstand the substantial joined to the respectively opposed lateral flanges and end of web plate 32 at the opposite ends of the form. These form the head and the foot of the finished casting, as will appear more fully hereinafter.

So much of the form just described constitutes an integral structure which in efliect comprises a central core for forming the interior wall faces, the horizontal and vertical wall surfaces and the tread and riser por tion of the cast stair structure.

Outer panels 26 are composed of angle-reinforced triangular weldrnents whose perpendicularly-related edge-s rest upon the respective horizontal flanges 38, 40 to complete the triangular trough or cavity for forming the sidewalls of the stair structure at either side of the stair flight. These outer panels merely rest in the trough formed by flanges 33, 4t) and are held in spaced relation to inner panels 24 by buttress plates 42 secured along the outer margins of flanges 38, 40.

At the opposite upper tips or corners of triangular panels 26, as viewed in FIG. 1 for example, the panels are truncated slightly. At the left, as seen in FIG. 1, a plate 44 extends across the form and is removably pinned as by taper pins 46, to the respective outer panels 26 and to the respectively adjacent flanges 38 at either side of the form. Similarly, at the upper righthand corner of the form as seen in FIG. 1, a plate 48 extends across the form and is removably secured, as by taper pins 50, at each of its ends to the respective side panels 26 and adjacent lateral flanges 40. Plate 48 forms the foot of the completed casting, and in the installed position of the stairway this foot is adapted to rest upon a sill or footing adjacent the outer face of the subgrade entrance. Plate 44 provides a beveled surface which in the installed position of the finished casting is disposed perpendicularly and facilitates grading to the level of the upper step.

After form 29 as thus assembled is filled with concrete and the latter is allowed to set, plates 44 and 4- are removed by withdrawing taper pins 46, 50, and outer panels 26 are then hoisted vertically sufiiciently to free the lower edges thereof from engagement behind the respective buttress plates 42, thus permitting the outer panels to be swung laterally away from the sides of the finished casting. The latter may then be lifted free of the form by a suitable hoist and sling arrangement attached to loops 52 or similar means embedded in the upper face of the casting, as seen more particularly in FIG. 6 of the drawings.

It is sometimes desirable to provide a crub along the inner edge of the top surface of the casting in its installed position, which curb serves not only to facilitate location and installation of a metal entrance hatch of the type commonly employed to enclose the upper end of the stairway, but also for preventing water from working back into and down along the inner side walls of the stair-way. For this purpose a removable plate 54 is laid in position along each flange 38, adjacent outer flanges 26, as seen more particularly in FIGS. 7 and 8. As there shown, plates 54 are made narrower than the width of the cavity adjacent plates 3-8, thereby producing curb 56 along that edge in the finished casting, as seen in FIG. 7. Plate 54 may also incorporate lugs 58 at spaced points along its length, which lugs form sockets in the upper face of the finished casting for the reception of expansion-type anchor lugs, not shown. These are employed to receive the bolts or other means used to secure the aforementioned entrance hatch over the stair struc ture. Plates 54 either drop free of the casting as the latter is hoisted from the form, or may be readily pried loose from the casting after it has been raised from the form.

The form structure shown in FIGS. 7 and 8 illustrates a further modification of the arrangement shown in FIGS. 1 through 5, in that outside panels 26 in this instance are secured in position on their respective flanges 4 38, by means of taper pins which pass through mating holes bored in the lower lip of the panels and respectively adjacent flanges 38, 40. This arangement is an obvious equivalent for the buttress plates 42 shown in the previous construction.

Another modification is illustrated in FIGS. 9 and 10 wherein the outer side panels 126 are employed as a means for lifting the finished casting from the form. In this instance the right-angularly related lower edges of outer side panels 126 are provided with in-turned flanges 127, 129, which extend inwardly less than the full width of the cavity adjacent the supporting flanges 138, 140, respectively. A filler strip 160 is permanently secured to flanges in complementary relation to in-turned flanges 129, whereby to provide a flush inner surface along the corresponding end face of the finished casting. No corresponding filler plate is provided along the adjacent flange 138 (see FIG. 10) so that a stepped surface along that face is provided, providing a curb 156 in the finished casting.

The lower edges of outer panels 126 are held in in proper position on their respective flanges 138, 140, by aligned holes and taper pins, similar to the arrangement shown and described in connection with FIGS. 7 and 8. In addition to the end plates 144, 148, at the upper corners of panels 126, a central transverse brace 162 is bolted to the panels at a point on the axis of the center of gravity of the finished casting. In this arrangement, the finished casting is lifted from the form by attaching a hoist to crossbrace 162 and raising the casting vertically to free it of the inner plates 124. The casting may then be lowered and tipped over in a direction causing it to rest on the leg formed by flange 127. Since the curb 156 is formed in the casting along this same face and the weight of the casting is thus supported by the curb, side panels 126 may then be easily removed on disengagement of bolts 16.4, by prying the panels from the outer faces of the finished casting to free flanges 127 from beneath the casting.

Essentially the same arrangement is shown in FIGS. 11 and 12 but in this instance filler plates are employed along the inner edge of both flanges 138, 140 and a curb-forming plate 154 is loosely positioned along the lower flange of side panels 126, similar to the arrangement shown and described in connection with FIGS. 7 and 8. This provides an alternate way of forming the curb 156 in the edge of the casting which is to be horizontal in the installed position of the stairway. Removal of the casting from the central portion of the form is accomplished in the manner described above.

In some instances it may be desirable to produce a stair structure of lesser depth and fewer steps than the maximum of which the form is capable. This can be readily accomplished in any of the forms here described without rebuilding the forms. In such a case, a weldment is provided for placement along flanges 38 of FIG. 1 for example, providing a false bottom to that wall of the cavity and across the end of web plate 32, whereby effectively to shorten the stair flight and side walls by an amount equal to one or more tread and riser sections, as may be required. These and similar changes in the foregoing specifically described embodiments illustrate typical modifications that may be made in the details of the form. It is to be understood, therefore, that the appended claims are intended to cover such modifications and the obvious equivalent thereof.

What is claimed is:

1. A form for casting a concrete subgrade stairwell and flight of stairs as a monolithic structure which comprises:

(a) a pair of generally right-triangular inner side panels;

(b) support means for disposing said panels in spaced,

vertically inclined planes with their apexes at the bottom and their hypotenuse edges substantially horizontal, the direction of inclination causing said panels to diverge slightly toward said apexes;

(c) a web plate permanently joined to and extending between said panels at their hypotenuse edges throughout the extent thereof, said plate having a saw-tooth conformation as viewed edgewise to correspond with the desired conformation of the treads and risers of the flight of stairs in the finished casting, and said hypotenuse edges of said inner side panels being similarly formed to mate with said web plate; each of said inner panels having laterally extending flanges permanently joined along their respective right-angularly related edges to form V- troughs on either side of said form, said flanges extending beyond the ends of said inner panels and web and having a filler panel at each of the opposite ends of said form, said filler panels extending between and being permanently joined to the opposed lateral flanges and to the corresponding end of said web plate;

(d) a pair of generally right-triangular outer side panels adapted to be removably received in and to mate with said lateral flanges on said inner panels in laterally spaced relation to said inner panels, thereby forming right-triangular prismatic voids corresponding to the side walls of the finished casting, the hypotenuse edges of said outer side panels being substantially linear and disposed horizontally above the plane of said web plate a distance sufiicient to provide the desired thickness of stair flight in the finished casting;

(e) and means for temporarily retaining said outer side panels against lateral displacement on said laterally extending flanges when fluid concrete is poured into said form, said retaining means being disengageable from said outer panels to permit the latter to be removed from the form after the concrete has set.

2. A form for casting a concrete subgrade stairwell and stair flight as a monolithic structure as defined in claim 1, which also includes a curb-forming plate loosely positionable along at least one opposite pair of said lateral flanges on said inner side panels.

3. A form as defined in claim 2, wherein said curbforming plates are provided with lugs in spaced relation along their extent, which lugs extend upwardly in the assembled form.

4. A form for casting a concrete subgrade stairwell and stair flight of monolithic construction as defined in claim 1, wherein said outer side panels are provided with laterally extending flanges along their right-angularly related edges, which flanges are directed inwardly toward said inner panels and overlie, in the assembled form, a

portion of the width of said lateral flanges on said inner panels.

5. A form as defined in claim 4, which includes hoist connections provided on said outer side panels adjacent the upper edges thereof along the axis of the center of gravity of the form and finished casting.

6. A form as defined in claim 4, which also includes a separable curb-forming plate loosely positionable along at least each of one opposite pair of lateral flanges on said inner side panels.

7. A form as defined in claim 6, wherein said curbforming plates are provided with lugs in spaced relation along their extent, which lugs extend upwardly in the assembled form.

References Cited by the Examiner UNITED STATES PATENTS 9/1864 Lyons 249-14 8/1966 Hulicki 249-14 

1. A FORM FOR CASTING A CONCRETE SUBGRADE STAIRWELL AND FLIGHT OF STAIRS AS A MONOLITHIC STRUCTURE WHICH COMPRISES: (A) A PAIR OF GENERALLY RIGHT-TRIANGULAR INNER SIDE PANELS; (B) SUPPORT MEANS FOR DISPOSING SAID PANELS IN SPACED, VERTICALLY INCLINED PLANES WITH THEIR APEXES AT THE BOTTOM AND THEIR HYPOTENUSE EDGES SUBSTANTIALLY HORIZONTAL, THE DIRECTION OF INCLINATION CAUSING SAID PANELS TO DIVERGE SLIGHTLY TOWARD SAID APEXES; (C) A WEB PLATE PERMANENTLY JOINED TO AND EXTENDING BETWEEN SAID PANELS AT THEIR HYPOTENUSE EDGES THROUGHOUT THE EXTENT THEREOF, SAID PLATE HAVING A SAW-TOOTH CONFORMATION AS VIEWED EDGEWISE TO CORRESPOND WITH THE DESIRED CONFORMATION OF THE TREADS AND RISERS OF THE FLIGHT OF STAIRS IN THE FINISHED CASTING, AND SAID HYPOTENUSE EDGES OF SAID INNER SIDE PANELS BEING SIMILARLY FORMED TO MATE WITH SAID WEB PLATE; EACH OF SAID INNER PANELS HAVING LATERALLY EXTENDING FLANGES PERMANENTLY JOINED ALONG THEIR RESPECTIVE RIGHT-ANGULARLY RELATED EDGES TO FORM VTROUGHS ON EITHER SIDE OF SAID FORM, SAID FLANGES EXTENDING BEYOND THE ENDS OF SAID INNER PANELS AND WEB AND HAVING A FILLER PANEL AT EACH OF THE OPPOSITE ENDS OF SAID FORM, SAID FILLER PANELS EXTENDING BETWEEN AND BEING PERMANENTLY JOINED TO THE OPPOSED LATERAL FLANGES AND TO THE CORRESPONDING END OF SAID WEB PLATE; (D) A PAIR OF GENERALLY RIGHT-TRIANGULAR OUTER SIDE PANELS ADAPTED TO BE REMOVABLY RECEIVED IN AND TO MATE WITH SAID LATERAL FLANGES ON SAID INNER PANELS IN LATERALLY SPACED RELATION TO SAID INNER PANELS, THEREBY FORMING RIGHT-TRIANGULAR PRISMATIC VOIDS CORRESPONDING TO THE SIDE WALLS OF THE FINISHED CASTING, THE HYPOTENUSE EDGES OF SAID OUTER SIDE PANELS BEING SUBSTANTIALLY LINEAR AND DISPOSED HORIZONTALLY ABOVE THE PLANE OF SAID WEB PLATE A DISTANCE SUFFICIENT TO PROVIDE THE DESIRED THICKNESS OF STAIR FLIGHT IN THE FINISHED CASTING; (E) AND MEANS FOR TEMPORARILY RETAINING SAID OUTER SIDE PANELS AGAINST LATERAL DISPLACEMENT ON SAID LATERALLY EXTENDING FLANGES WHEN FLUID CONCRETE IS POURED INTO SAID FORM, SAID RETAINING MEANS BEING DISENGAGEABLE FROM SAID OUTER PANELS TO PERMIT THE LATTER TO BE REMOVED FROM THE FORM AFTER THE CONCRETE HAS SET. 